Railway signalling system for the automatic control op trains



April 19, 1966 P. GRAVIN 3,2

RAILWAY SIGNALLING SYSTEM FOR THE AUTOMATIC CONTROL OF TRAINS Filed Aug. 10, 1961 4 Sheets-Sheet 1 FIGJ INVENTOR PAUL GRAVIN BY R AGE P. GRAVIN 3,247,371

RAILWAY SIGNALLING SYSTEM FOR THE AUTOMATIC CONTROL OF TRAINS April 19, 1966 4 Sheets-Sheet 2 Filed Aug. 10, 1961 FIG.2

R m N w N w A R 6 w m 3 l G F AGENT April 19, 1966 P. GRAVIN 3,247,371

RAILWAY SIGNALLING SYSTEM FOR THE AUTOMATIC CONTROL OF TRAINS Filed Aug. 10, 1961 4 Sheets-Sheet- 5 FIGJ.

INVENTOR PA UL GRAVIN 0L OF TRAINS April 19, 1966 P. GRAVIN RAILWAY SIGNALLING SYSTEM FOR THE AUTOMATIC CONTR 4 Sheets-Sheet 4 Filed Aug. 10, 1961 31b h Pb .43 43a 43b 1.2 Pg I L.

INVENTOR PA UL GRA VIN BY M a United States Patent 3,247,371 RAILWAY SIGNALLING SYSTEM FOR THE AUTOMATIC CONTROL OF TRAINS Paul Gravin, Paris, France, assignor to North American Philips Company, llnc., New York, N.Y., a corporation of Delaware Filed Aug. 10, 1961, Ser. No. 130,602 15 Claims. (Cl. 246-63) This invention relates to a railway signalling system for the automatic control of trains.

Optical semaphores arranged alongside the track have various disadvantages. For example, the driver gets a poor view of the semaphores in the event of snow, fog and the like. If a semaphore gives the indication slow down, the train is required to maintain the reduced speed until the next semaphore, even if the conditions giving rise to the reduced speed have in the meantime disappeared.

It is known to supply electric signals to the rail circuit, which signals can be received by the train (cab signalling).

These signals may, for example, give an indication about the speed which is allowed. The arrangement may, for example, be such that the train driver receives an optical or an acoustic indication, with the result that if he does not respond thereto within a given time, by reducing the speed, the brakes of the train are automatically actuated until the train has come to a complete standstill. An advantage of these methods is that a continuous signalling is obtained, so that during the travel through a section the speed can be adapted to modified circumstances.

With a given system an electric signal is fed to the rail circuit as long as no speed restriction is required, whereas in the absence of the signal a reduced speed is to be maintained.

With a different system an electric dont brake signal is normally fed to the rail circuit and the brakes of the train are automatically actuated when this signal is lacking. If the non-reception of this signal is due to a disturbance, the train will therefore also be stopped.

In many cases it is not necessary for the speed of the train to be reduced as soon as it enters a given section, since it would otherwise travel through the whole section with the reduced Speed. If, for example, a train has to ride over a switch point which is in the reverse condition, it is suflicient for the train to have the reduced speed when coming up to the point, but it is not necessary for the speed to be reduced earlier, which means that the reduction of the speed need take place only at the ultimate instant. In the normal condition of the switch point, as a rule, no speed reduction is required.

The invention relates to a system in which fixed stations along the track can feed a characteristic dont brake or other command speed type signal to the rail circuit, or in which they do not supply such a signal, and in which the trains are equipped with means for receiving these signals from the rail circuit in front of the train for actuating the brakes when the signal is not received. In accordance with the invention, provision is made of a main station and of one or more substations located at such distances from the main station that, when a train starts braking when passing by a substation, it has assumed a given, desired speed, when reaching a given point of the track. The main station further comprises means for emitting a characteristic signal for the substation in accordance with the said speed, the dont brake signal being fed to the rail circuit at the reception of the said signal by the substation.

Since a train can receive a signal only from the rail circuit in front of the train, the reception of the dont brake signal falls off as soon as the train passes by the substation, concerned, so that the train starts braking.

i for example, substation R;,,,

The invention will be described more fully with reference to the drawing, in which: I

FIG. 1 shows a geographic survey of two adjacent track sections. 3

FIG. 2 shows diagrammatically the circuit arrangement of the substation.

FIG. 3 shows diagrammatically the circuit arrangement of the main station.

FIGS. 4 and 5 show diagrammatically the circuit arrangement of an engine and FIG. 6, shows a track section through which the trains can ride in two different directions.

FIG. 1 shows two track sections V and V the rails of which are insulated at both ends in known manner from those of adjacent sections. Alongside the track optical semaphores S S and S are arranged, which may form part of an automatic block system. The trains travel in the direction of the arrow 1, i.e. from the left to the right. At the right-hand end of each section is ar ranged a main station E and E respectively, which stations are capable, according to need, of feeding signals having a frequency F F F or F, to the associated rail circuit. The signal having the frequency F constitutes the dont brake signal. Along the track are furthermore arranged substations R R R R R and R which are capable of receiving the control-signals emitted by the two main stations. The stations R and R are only sensitive to the frequency P the stations R and R only to the frequency F and stations R and R to the frequency F If a train is allowed to pass by a given semaphore, for example S,,, with a given speed or is re quired to come to a standstill in front of this semaphore, the main station emits a corresponding signal. If the train has to stop in front of the semaphore S the main station emits the frequency F This signal is received by the substation R so that this substation supplies the dont brake signal of the frequency P te the rail circuit. With a desired speed'reduction to 30 km. an hour, the main station emits the frequency F which is received by the substation R which then-emits the dont brake signal F Similarly, with a speed reduction to 90 kms. an hour, the main station E will emit the frequency F so that at the substation R the dont brake signal F is emitted. If there is no speed reduction the main station E itself emits the dont brake signal F If, by way of example, a speed reduction to 30 kms. an hour is desired, the dont brake signal F will be emitted by the'substation R As long as the train is on the left-hand side of this station, it receives the said signal, but as soon as the station is passed by, the reception falls oif, on the one'hand since the train can receive only signals from the rail circuit in front of the engine and on the other hand since the short-circuit of the rails formed by the train prevents signals from being transmitted from the main station E to the substation R In the train the brakes are then actuated. The various substations are disposed at such distances from the semaphore S that, if a train travelling with normal speed starts braking when reaching a substation, the train has assumed the desired speed when reaching the semaphore S or has come to a standstill. The distance from a substation to the semaphore will therefore be smaller according as the permissible speed is higher.

FIG. 2 shows a possible arrangement of a substation, If the main station E emits a signal of the frequency F and if a train is present within the section V on the left-hand side of the substation R,,, a current with the signal frequency will pass through the rail circuit formed by the train and the rails.

As a result, induction voltages are produced in the collecting coils SS; and SS coupled inductively with the rails. These voltages are fed via the filter 1, which only passes the frequency F and the transformer 2 to the receiver 3. The signal voltages amplified by the receiver cause the relay 4 to respond. The relay connects, via its make contact 4a, the supply source V to the generator 5, which then produces an oscillation signal with a frequency F and feeds it via the make contact 4b of the relay 4 and the filter 6, whichv allows this frequency to pass, to the rail circuit. If a disturbance occurs in the substation, a trainwill start braking immediately upon entering the section, since the dont brake signal is lacking. FIG. 3 showspart of the circuit arrangement of a main station. In accordance with the position of the switch points a train may, for example, have a speed of 30 kms. an hour when passing by the semaphore S if the track V is to be followed, a speed of 60 kms. an hour if the track V is to be followed, or a speed of 90 kms. an hour, or any speed, if the train has to ride straight along the track ,V in accordance with the optical indication given by the semaphore S. The station comprises a number of relays 11, 12, 13 and 14, which can be energized in known manner by :means'not shown in accordance with the desired speed of the train. Relays 11 through 14 are shown in the deene rgized position with contact arms 11a through 14a closed on their respective break contacts B. The make contacts of relays 11 through 14 are designated by the reference numeral M. If none of the relays 1114 is energized, the relay 25 is energized via the break contacts B and contact arms 11a, 12a, 13a and 14a and the battery U. However, in the case of the energization of one of the relays 11, 12, 13 or 14, the corresponding relay 21, 22, 23 or 24 is energized via the associated make contact M and contact arms 11a, 12a, 13a or 14a. The contact arms 21a, 22a, 23a, 24a and 25a switch in or out capacitors C C C and C associated with a resonant circuit (not shown) of the generator 10, so that the frequency produced by the generator 10 depends upon the state of energization of the relays. If one of the relays 11, 12, 13 or 14 is energized, the frequency P F F or P will be produced, whereas, if none of the relays is energized, the frequency F corresponding to the ,dont' brake signal is produced. The output oscillations of the generator are transferred via the transformer 26 to the rails. FIG. 4 shows a possible circuit arrangement in an engine. It comprises a collecting device 30, having two coils which are arranged in front of the foremost axle of the engine in the proximity of the rails and are inductively coupled therewith, so that signal currents in the rails produce induction voltages in the coils. Such a receiving arrangement is known per se and is employed, for example, in the so-called cab signalling system. Signals of the dont brake frequency, F are amplified by the amplifier 31 and, if desired subsequent to rectification, they energize the relays 32' and 32 bis. Via the make contacts 32a and 32a the indicator lamp 33 receives current, so that it glows, while at the same time relay 34 is energized. Via make contact 34a the device 35 is energized, which holds the braking device out of operation. If the dont brake signal is no longer received, the various relays fall off, so that the brakes are actuated and the lamp 33 extinguishes. switch 36, the driver can hold the device 35 energized, so that the brakes do not become operative. Under certain conditions it may be desirable to put the automatic braking device out of operation at stations where it is not efficient to supply the dont brake signal owing to the presence of many switch points. The driver can then take over the .control manually. In this case a signal with an auxiliary frequency F instead of a frequency F is supplied to the rails at the entrance of a station. This signal also passes through the amplifier 31, so that the relay 37 is energized. The relay 37 closes a holding circuit for itself via its own make contact and Winding M If desired, by actuating a I 4 in series with the break contacts 32b and 32b of the relays 32 and 32. At the same time, via the make contact 37a and the break contacts 32c and 320, an energizing circuit of relay 34 and the lamp 33 is closed independently of the make contacts 32a and 3211* As described above, the brakes of the train are actuated when the dont brake signal falls off. This will therefore also be the case where the absence of the signal is due to a disturbance. Consequently, a failure in the system cannot give rise to accidents. The conditions are worse when the dont brake signal is present at a place where it is not supposed to exist, for example,,if the dont brake signal is transmitted from one track section tothe following section owing to a defective insulation between two adjacent rail sections. In this case serious accidents may occur.

In accordance with the invention, this disadvantage can be obviated by using relatively different dont brake signals for adjacent sections. In principle relatively different signals may be used for the various sections, but in practice, it has been found that a simultaneous defect of the insulations at the two ends of a section is extremely improbable, so that it is sufficient to use, in total, two different dont brake signals, which alternate from section to section. The main station l-E and the substations R R and R of FIG. 1 will in this case emit a signal with a frequency F as a dont brake signal and the Stations E 1, Rn R and R +1 emit a signal with a frequency P In order to change over automatically in the train from one dont brake signal to the other, auxiliary transmitting devices Z and Z are provided at the inputs of each section. These devices comprise inductive coupling members T and T so that, when a train passes by, the signals produced by the auxiliary transmitting devices Z and Z having, for example, a frequency of F9 and F are transferred to the collecting coils 30 of the engine.

FIG. 5 shows a receiving circuit in an engine having four frequency selective amplifiers 31a, 31b, 40a and 4012, which allow only the frequencies F F F? and F to pass. The collecting coils 30 are again coupled inductively. with the rail'circuit. When the train enters the section V,,, the transmitting device Z, transmits a control-signal via the coils 30 and the amplifier 40a to the right-hand winding of the bistable polarisation relay 41, which is thus brought into a given state, and which is held after the signal has disappeared. In a similar manner, when the train enters the section V the transmitting device Z transmits, via the coils 30 and the amplifier 40b, a control-signal to the left-hand winding of the relay 41, which is thus moved into the other state. In the same manner the dont brake signal with the frequency F3 in the section V will energize the relay 42 via the amplifier 31a, whereas the dont brake signal with the frequency F in the section V energizes the relay 43 via the amplifier 31b. The relay 41 controls a changeover contact 41a, so that in one state of the relay an energizing circuit is closed for the relay 34 and the indicator lamp 33 via contact 41a, make contact 42a of relay 42 and break contact 43a of relay 43, whereas in the other state of relay 41 the energizing circuit is formed via contact 41a, break contact 42b of relay 42 and make contact 43b of relay 43. The relay 34 corresponds to relay 34 of FIG. 4, which means that in the non-energized state of the relay 34 the braking device of the train becomes operative. As the train travels through the section V the relay 34 will be energized as long as only the dont brake signal with the frequency F is received. In a similar manner the relay 34 is energized at the reception of the dont 'brake signal F within the section V If one of the dont brake signals is received, neither of the relays 42 or 43 is energized and relay 34 will not be energized either since the two potential energizing circuits are then open, irrespective of the section in which the train is located. However, it due to a defective insulation between successive sections the two dont brake signals with the frequencies F and F respectively are received simultaneously, the relays 42 and 43 will consequently be energized simultaneously. In this case relay 34 does not receive current since its two potential energizing circuits include a break contact of one of the relays 42 and 43. Consequently, the train will come to a standstill. In this case the relay 44 is energized via the make contacts 42c and 430 of the relays 42 and 43, so that further means (not shown) give an alarm.

FIG. 6 shows the use of the invention in a line section V, in which a train can travel in two difierent directions indicated by the arrows f and f The substations R and R and the main station E provide the speed control at the end of the section for the travelling direction of the arrow f whereas the stations E R and R correspond to the opposite direction. The two signalling devices may be simultaneously operative, 'while for the two signalling systems the same dont brake signal, for example, with the frequency F may still be employed. It will be assumed, by way of example, that for the travelling direction f a speed restriction prevails so that under the control of the main station E, the substation R emits the dont brake signal as described with reference to FIG. 1, whereas for the opposite direction the station R emits the dont brake signal under the control of the main station E If a train enters the section V in the direction of the arrow f first the axles of the train will short-circuit the rails in the stretch between the stations E,, and R and the transmission of the controlsignal from the station E,, to the substation R will be interrupted and the station R will terminate the emission of the dont brake signal. Since the collecting coils 30 on the train are arranged on the front side of the engine, the dont brake signal emitted by the station R can, however, be received by the engine. If the train has passed by the station R g, the transmission of signals from the station E to the station R g will be restored it is true, but the dont brake signal then emitted by the station R cannot be received by the collecting coils on the front side of the train since the axles of the train behind these coils produce a short-circuit between the rails. The dont brake signal from the station R will, however, be received by the coils until the engine has passed by the station R after which, as described above, this signal is no longer received and the brakes are actuated. In order to signal from the two main stations E and E to the associated substations, the same signals may, if desired, be used, since the signalling is automatically removed in the undesired direction by the presence of a train. Within the scope of the invention the system may be varied in different ways. The various signals may, for example, be formed by coded pulse trains instead of being formed by different frequencies. Therefore, it is to be understood that various changes and modifications are possible within the scope of the appended claims.

What I claim is:

1. A railway signalling system for controlling the speed of a train at a given point comprising a track circuit having a plurality of sections insulated from one another, a main station, a plurality of secondary stations arranged along the track circuit within a given section thereof which is insulated from the adjacent sections, means at said main station for transmitting to said given section of track circuit identification signals individual to the various secondary stations thereby to selectively actuate a given one of said secondary stations in accordance with a desired train speed at said given point, each of said secondary stations comprising control means responsive to its individual identification signal and means responsive to said control means for transmitting a characteristic command speed signal to said given section of the track circuit, and means in said train responsive to said command speed signal received from the track circuit for automatically adjusting the train speed.

2. Apparatus as described in claim 1, wherein said identification signals comprise electrical signals of different frequencies.

3. A railway signalling system for the automatic control of a train comprising a track circuit, a main station, a plurality of secondary stations arranged along the track circuit, means at said main station for transmitting identification signals individual to the various secondary stations and means for transmitting a characteristic command speed signal to the track circuit, each of said secondary stations comprising control means responsive to its individual identification signal and means responsive to said control means for transmitting the command speed signal to the track circuit, and means in said train responsive to said command speed signal for automatically adjusting the train speed.

4. A railway signalling system for the automatic control of a train comprising a track circuit, a main station and a plurality of substations arranged along the tracks and interconnected by means of said track circuit, means at said main station for transmitting to the track circuit identification signals to selectively energize individual ones of said substations, individual signal pickup means connected to each of said substations and located at predetermined positions along the tracks, each of said substations comprising control means responsive to its identification signal and means responsive to said control means for transmitting a characteristic dont brake signal to the track circuit, and receiving means in said train responsive only to the dont brake signals received from the track circuit in front of the train and means responsive to the absence of the dont brake signal to actuate the brakes.

5. A railway signalling system for the automatic control of a train comprising a track circuit section, a main station and a substation interconnected by means of said track circuit, insulation means at either end 05 said track circuit section for insulating said section from the adjacent track circuit sections, means at said main station for transmitting to the track circuit an identification signal individual to said substation and a dont brake signal characteristic of said track circuit section, means at said adjacent sections for transmitting to said adjacent track circuit sections a characteristic dont brake signal difterent from the dont brake signal of said track circuit section, said substation comprising control means responsive to said identification signal and means responsive to said control means for transmitting said characteristic dont brake signal to the track circuit, means located at the entrance of the track section for transmitting a control signal to a passing train, said train comprising receiving means responsive to the dont brake signal and means responsive to said control signal for conditioning the receiving means to the reception of the dont brake signal characteristic of said track section, and means for actuating the brakes whenever the dont brake signal is absent or upon receipt of a dont brake signal characteristic of an adjacent section of said track circuit.

6. A railway signalling system for the automatic control of a train comprising a track circuit divided into track sections, a main station and a plurality of substations for each track section located along the tracks and interconnected by means of said track circuit, means at said main station for transmitting to the track circuit identification signals individual to the various substations and a characteristic dont brake signal, each of said substations comprising control means responsive to its identification signal and means responsive to said control means for transmitting a characteristic dont brake signal to the track circuit, said characteristic dont brake signal being different for adjacent track sections, means for transmitting a control signal at the beginning of each track section to a passing train, said train comprising receiving means responsive only to the donft brake, signals received from the track circuit in front of the train and means responsive to said control signal to condition the receiving means to the reception of the dont brake signals characteristic of the track section the train is entering and means for actuating the brakes whenever the dont brake signal is not received.

7. Apparatus as defined in claim 6, in which two distinct dont brake signals are utilized, said dont brake signals alternating from section to section along the track.

8. Apparatus as defined in claim 6, in which said train receiving means further comprises means responsive to the simultaneous receipt of two different dont brake" signals for actuating the train brakes and an alarm device.

9. A railway signalling system for the automatic control of a train comprising a track circuit divided into track sections, first and second main stations for each track section and a plurality of associated substations for each of said main stations located in the vicinity of the ends of said track section, said main stations and substations being interconnected by the track circuit within its track section, means at each of said main stations for transmitting to the track circuit identification signals individual to its various associated substations and a characteristic dont brake signal in accordance with the desired train speed in the two opposite directions of travel, each of said substations comprising control means responsive to its identification signal and means responsive to said control means for transmitting a characteristic dont brake signal to the track circuit, said train comprising receiving means responsive only to the dont brake signals received from the track circuit in front of the train and means to actuate the brakes if the dont brake signals received from the track circuit in 10. A railway signal system for the automatic control of a train, comprising -a track circuit having an entrance section and an exit section, a main station having means for coupling electric signals to said track circuit, which means are located at said track circuit exit section, a secondary station having electric signal pickup means located along the entrance section of said track circuit, means at said main station for producing an identification signal individual to said secondary station and a characteristic command speed signal for controlling train speed, means at said main station for selectively transmitting said produced signals to said track circuit, said secondary station further comprising control means responsive to said identification signal individual thereto for producing a control signal and means responsive to said control signal for transmitting a command speed signal to the track circuit, and means in said train responsive to said command speed signal for adjusting the train speed.

11. A railway signal system for the automatic control of a train comprising a track circuit section having insulation means at either end thereof for insulating said section from adjacent sections of the track circuit, a main station having means for coupling alternating current signals to said track circuit section, said coupling means being located towards the exit end of said track section, first and second secondary stations each having signal pick-up means located in spaced relationship along said track circuit section in advance of said main station coupling means, means at said main station for producing alternating current identification signals individual to each of said first and second stations and a characteristic command speed signal for controlling train speed, means at said main station for selectively transmitting said produced signals to said track circuit in accordance with a desired train speed at a given location in said track circuit, each of said secondary stations comprising control means responsive only to its individual identification signal for producing a control signal and means responsive to said control signal for transmitting a command speed signal to the track circuit, signal pick-up means mounted on the front end of said train in coupling relationship with said track circuit for receiving signals therefrom and i 8 means in said train responsive to the command speed signal received for adjusting the train speed.

12. A railway signal system for train control, comprising a track circuit section insulated at either end thereof from adjacent sections of track circuit, a main station and a substation located within said section and electrically interconnected by means of said track circuit said substation being located in advance of said main station whereby for a given direction of train travel over said track section said train passes said substation before passing said main station, means at said main station for producing an identification signal individual to said substation and a command speed signal characteristic of said track section for controlling train speed, means at said main station for selectively transmitting said produced signals to said track circuit in accordance with a desired train speed at a given location in said track circuit, said substation comprising control means responsive to its said identification signal and further comprising means responsive to said control means for transmitting said characteristic command speed signal to the track circuit upon receipt of said identification signal at said substation, means located at the entrance of said track section in advance of said substation for transmitting a control signal to a passing train, said train comprising receiving means responsive to said characteristic command speed signal, said train receiving means further comprising means responsive to said control signal for conditioning said receiving means for the reception of the command speed signal characteristic of said track section and means [for actuating the brakes upon receipt of a command speed signal characteristic of another section of said track circuit.

13. A railway signal system for train control, comprising a track circuit section insulated at either end thereof from adjacent sections of track circuit, a main station having means for coupling alternating current signals to said track circuit section, first and second secondary stations each having signal pick-up mean-s located in spaced relationship along said track circuit section in advance of said main station coupling means, means at said main station for producing alternating current identification signals individual to each of said first and second stations and 'a characteristic command speed signal for controlling train speed, means at said main station for selectively transmitting said produced signals to said track circuit in accordance with a desired train speed at a given location in said track circuit, each of said secondary stations comprising control means responsive only to its individual identification signal and further comprising means responsive to said control means for transmitting said characteristic command speed signal to the track circuit upon receipt of said identification signal, means located at the entrance of said track section in advance of said stations for transmitting a control signal to a passing train, said train comprising receiving means responsive to said characteristic command speed signal, said train receiving means further comprising means responsive to said control signal for conditioning said receiving means for the reception of the command speed signals characteristic of said track section and means for actuating the brakes upon receipt of a command speed signal characteristic of another section of said track circuit.

14. Apparatus as described in claim 13 wherein the track circuit comprises a plurality of track circuit sections insulated from one another, means in alternate ones of said sections for transmitting a first characteristic command speed signal to said sections and means at the other alternate ones of said sections for transmitting a second characteristic command speed signal to said other alternate sections, means located at the entrance of each of said track sections in advance of said secondary stations for transmitting a characteristiccontrol signal to a passing train, alternate ones of said control signal transmitting means producing a first characteristic control signal for said alternate track sections and alternate other ones of said control signal transmitting means producing a second characteristic control signal for the other alternate ones of said track sections, and said train receiving means comprising det-ecting mean-s responsive to said first and second control signals for conditioning said receiving means for the reception of one or the other of said first and second command speed signals.

15. A railway signal system for train control, comprising a track circuit divided into first and second sections separated by insulation means, each of said sections comprising a main station having means for coupling alternating current signals to said track circuit section, first and second secondary stations each having signal pick-up means located in spaced relationship along said track circuit section in advance of said main station coupling means, means at said first section main station for producing alternating current identification signals individual to each of said first section first and second secondary stations and a first characteristic command speed signal individual to said first section for controlling train speed, means at said second section main station for producing alternating current identification signals indi vidual to each of said second section first and second secondary stations and a second characteristic command speed signal individual to said second section for controlling train speed, means at each of said main stations for selectively transmitting said produced signals to said track circuit section in accordance with a desired train speed at a given location in said track circuit, each 10 of said secondary stations comprising control means responsive only to its individual identification signal and further comprising means responsive to said control means for transmitting said characteristic command speed signal to the track circuit upon receipt of said identification signal, first means located at the entrance of said first section and second means located at the entrance of said second section for transmitting first and second control signals, respectively, to a passing train, said train comprising receiving means selectively responsive =to said first and second characteristic command speed signals, said train receiving means further comprising means responsive to said first and second control signals for selectively conditioning said receiving means for the reception of the command speed signal characteristic of the track circuit section the train is entering, and means in said train responsive to the simultaneous receipt of said first and second command speed signals for actuating the train brakes.

References Cited by the Examiner UNITED STATES PATENTS 2,635,182 4/1953 Judge 246-3 X 2,816,218 12/1957 Rees et al. 246-5 2,816,219 10/1957 Ihrig 246-34 2,915,623 12/1959 Hughson 246-182 ARTHUR L. LA POINT, Primary Examiner. LEO QUACKENBUSH, EUGENE G. BOTZ, Examiners. 

1. A RAILWAY SIGNALLING SYSTEM FOR CONTROLLING THE SPEED OF A TRAIN AT A GIVEN POINT COMPRISING A TRACK CIRCUIT HAVING A PLURALITY OF SECTIONS INSULATED FROM ONE ANOTHER, A MAIN STATION, A PLURALITY OF SECONDARY STATIONS ARRANGED ALONG THE TRACK CIRCUIT WITHIN A GIVEN SECTION THEREOF WHICH IS INSULATED FROM THE ADJACENT SECTIONS, MEANS AT SAID MAIN STATION FOR TRANSMITTING TO SAID GIVEN SECTION OF TRACK CIRCUIT IDENTIFICATION SIGNALS INDIVIDUAL TO THE VARIOUS SECONDARY STATIONS THEREBY TO SELECTIVELY ACTUATE A GIVEN ONE OF SAID SECONDARY STATIONS IN ACCORDANCE WITH A DESIRED TRAIN SPEED AT SAID GIVEN POINT, EACH OF SAID SECONDARY STATIONS COMPRISING CONTROL MEANS RESPONSIVE TO ITS INDIVIDUAL IDENTIFICATION SIGNAL AND MEANS RESPONSIVE TO SAID CONTROL MEANS FOR TRANSMITTING A CHARACTERISTIC COMMAND SPEED SIGNAL TO SAID GIVEN SECTION OF THE TRACK CIRCUIT, AND MEANS IN SAID TRAIN RESPONSIVE TO SAID COMMAND SPEED SIGNAL RECEIVED FROM THE TRACK CIRCUIT FOR AUTOMATICALLY ADJUSTING THE TRAIN SPEED. 